Hand-shears for cutting sheet metal.



No. 639,874. Patented D60. 26, 1399.

- G. THUILLIER.

HAND SHEARS FOR CUTTING SHEET METAL.

2 Sheets Sheet I,

(No Model.)

No. 639,874. Patented Dec. 26, I899.

a. THUILLIER.

HAND SHEARS FOR CUTTING SHEET METAL.

(Application filed July 19, 1899.) (No Model.) 2 Sheets-Sheet 2.

m: yonms PEYER$ ca. we're-mum. wAsnlut-rou. mc.

UNITED STATES PATENT OFFICE.

GEORGES THUILLIER, OF NOGENT-EN-BASSIGNY, FRANCE.

HAND-SHEARS FOR CUTTING SHEET METAL.

SPECIFICATION forming part of Letters Patent N 0. 639,874, datedDecember 26 1899. Application filed July 19, 1899. Serial No. 724,380.(NOdJlOdBL) To all whom it may concern:

Be it known that I, GEORGES THUILLIER, manufacturer, a citizen of theRepublic of France,and a resident of Nogent-en-Bassigny, I'Iaute-Marne,France, have invented a new and useful Improvement in Hand-Shears forCutting Sheet Metal and other Analogous Hard Materials, of which thefollowing is a specification.

This invention consists in the novel construction of hand-shearshereinafter described and claimed, whereby a more effective opera tionis obtained, especially in cutting sheet metal and other hard substancesand in making cuts on curved lines.

The invention is illustrated by theacco|npanying drawings, in which-Figure 1 is a perspective View of the operative portions of the bladesof a pear of shearsof ordinary construction; Fig. 2, a similar view ofthe corresponding parts of a pair of shears embodying my invention; Fig.3, a side View showing the blades open; Fig. 4, a side view showing theblades closed; Fig. 5, a transverse section through the line 5 5 of Fig.4 Fig. 6, a side view of the blades of the same shears, illustrating theact of cutting a piece of sheet metal; and Fig. 7 a section on the line1 2 of Fig. 6.

It is known that ordinary hand-shears do not permit of hard materiaISSuch as sheetzinc, tin, &c.being properly cut to any desired curve. Infact, if with these shears it is desired to cut a sheet of metal ofconcave curve, for example, as shown in Fig. 1 of the drawings, the part,2 of this sheet which is already cut will be brought to bear againstthe wide face y of the upper blade, so that in order to be able tocontinue to efiect the cut it is necessary to incline the shears in sucha way as to permit of this part z passing over the blade by bending orcurling itself more or less; but the shears will then be in anabsolutely unfavorable position for cutting, and can consequently onlyproduce defective work. These hand-shears are, further, always difficultto employ for cutting hard materials, even when such cutting is to beeffected in a straight line, because the force to be exerted by theworkman increases rapidly as the point of cutting becomes farther andfarther removed from the axis of articulation of the blades. Thisis thecase for two reasons, the first being that even if the angle which theblades form during the cut remain constant the force to be exerted bythe workman would always increase, on account of the the blades, so thatthe force to be exerted further increases considerably from this fact.It is evidently the fact that the less this angle the more rapid thecut, and consequently the work to be effected in a given time increasesconsiderably.

By my improved shears the two disadvantages above indicated areobviated. These shears (shown in Figs. 2, 3, 4, and 5) enable thecutting to be effected without bending or curling of the part a of thesheet, even when following very accentuated concave curvesin sheets ofany hard material, from the fact that the upper blade is shaped in sucha way that the metal out can glide and pass over it without having tobend itself. Further, they render the out in all cases easy, because,owing to the conformation of the upper blade, the force exerted foreifecting the cut remains constant, the angle of the blades at the cut=ting-point increasingin proportion to the closing of the shears.

It will be seen that the upper blade a instead of being high and flatand with a straight edge like the other blade I) is of less height andof lenticular section, so as to present to the side of the lower bladenota straight and vertical edge, but a convex inclined surface, overwhich that part a of the sheet already out can easily pass and slide.This it does without having to bend or curl, because that part of theupper blade which is behind the cutting-point descends beneath the levelof the upper edge of the under blade by reason of the movement of theclosing of the blades. This descent of the upper blade beneath thecutting edge of the other blade becomes particularly pronounced whenthis upper blade is curved or bent in the direction of its length, asshown in the drawings. It is also this curved form in the longitudinaldirection which enables me to increase the angle which the blades formwith the cutting-point as this point becomes farther and farther removedfrom the axis of articulation c. It will, in fact, be seen in Figs. 3and 4 that the angle d, formed by the blades with the cutting-point whenthe shears are nearly closed, is greater than the angle a, which theyform at the moment when they begin to out.

The cutting action is best illustrated by Figs. 6 and 7, the out beingmade on the curved line '0 w 3 in Fig. 7 having the radius R. The part y00 has been already cut, and the abovementioned views show clearly thatpart 2' of the plate from which the out has been made resting flat onthe straight edge of the blade 19, becauseit has not been pushed asideby the blade a, but has been able to pass above the face of the blade 19without touching it. It may be understood by a simple inspection of Fig.7 that the radius R, according to which the cut is made, cannot be lessthan the radius r of the curvature m 'n 0 of the inner surface of theblade a. If, then, this radius r is very short, sheets may be cut onvery accentuated concave curves. It will be understood, however, that myscissors may cut in straight lines or on convex curves. As to theexternal curvature m p 0 of the blade a, it is selected to give theblade the desired thickness and solidity. It need not be the same asthat of the internal surface.

I claim- A pair of shears comprising in combination two articulatedblades one of which has a straight edge and a flat inner face and theother of which has its inner face of lenticnlar transverse profile andat an inclination to the face of the straight blade, substantially asherein described. a

In testimony that I claim the foregoing as my inventionl have signed myname, in presence of twowitnesses, this 1st day of July,

GEORGES TI-IUILLIER. \Vitnesses:

ALCIDE FABE, GEORGES CABABY.

